Liquid crystal display devices are characterized by thin profile, lightweight and low power consumption, and are widely used in various fields. The display performance thereof has advanced dramatically over the years, and now even surpass CRTs (Cathode Ray Tube).
A display type of a liquid crystal display device is determined depending on how liquid crystals are aligned in a cell. Conventionally known display types of liquid crystal display devices are, for example, a TN (Twisted Nematic) mode, an MVA (Multi-domain Vertical Alignment) mode, an IPS (In-Plane Switching) mode and an OCB (Optically self-Compensated Birefringence) mode.
Liquid crystal display devices with such display types have been mass produced. Particularly liquid crystal display devices in a TN mode are widely used by the general public. However, liquid crystal display devices in a TN mode require improvement in terms of increasing the response speed and viewing angle.
Meanwhile, in an MVA mode, slits are formed in a pixel electrode of an active matrix substrate, and protrusions (ribs) for controlling the alignment of liquid crystal molecules are disposed in the counter electrode of the counter substrate, so that fringe fields generated by these slits and ribs disperse the alignment direction of the liquid crystal molecules into a plurality of directions. An MVA mode implements a wide viewing angle by dividing the directions, where liquid crystal molecules tilt down when a voltage is applied, into a plurality of types (multi-domains). Since an MVA mode is a vertical alignment mode, higher contrast can be obtained compared with TN, IPS and OCB modes. However, an MVA mode requires improvements in terms of simplifying manufacturing steps, and also in increasing the response speed, just like the case of a TN mode.
With regard to liquid crystal display devices of an MVA mode and IPS mode, there has been disclosed a substrate for a liquid crystal display device comprising a substrate that is disposed opposite to a counter substrate and holds liquid crystal with the counter substrate, a bus line formed on the substrate, a switching element connected to the bus line, a stripe-shaped electrode connected to the switching element, and a space. The stripe-shaped electrode and the space are parallel to the bus-line. The substrate has a pixel electrode in which the width of the stripe-shaped electrode in the neighborhood of the bus line is narrower than the width of an electrode located at an inner side of the stripe-shaped electrode (see, for example, Patent Document 1).
In order to solve the process problems of an MVA mode, a vertical alignment mode “Trans Bend Alignment (TBA) mode” has been developed. In TBA mode, p-type nematic liquid crystals are used as a liquid crystal material. Further, in a TBA mode, a transverse electric field is generated by using at least two kinds of electrodes such as a comb-shaped electrode, and the liquid crystals are driven by the transverse electric field so that the alignment azimuth of the liquid crystal is set. TBA mode can maintain a high contrast due to the vertical alignment. Moreover, TBA mode has a simple pixel configuration because it does not require alignment control using protrusions. Further, TBA mode is excellent in viewing angle characteristics.
Meanwhile, in a TBA mode, upon application of voltages, the liquid crystal molecules aligned in the vertical direction to the substrate surface exist at about the center between the two kinds of electrodes. For this reason, in the observation from the front side of the panel, the area looks as a dark line.
Patent Document 1: JP-A 2003-177418